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Calibration Questions

Discussion in 'AS 91XX - Aerospace Quality Standards' started by Roland Deschain, Mar 11, 2024.

  1. Roland Deschain

    Roland Deschain New Member

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    Hello. First time posting here, so apologies if this is out of the norm, or not the correct space.

    I am a QC tech in a machine shop that has been ISO 9001 certified for about 12 years.

    The owner has let everyone know his intention to get AS9100 certified, but we have trouble following the 9001 standards as it is.

    We do not have any thread gages in our calibration system. They are all marked as reference only, even the ones used for final inspection.

    The owner is now asking the QC Manager to calibrate our master gage blocks and rings using our CMM, instead of sending them out to a lab.

    We have a keyence VR series scanner that also has not been calibrated in 2 or 3 years.

    I don't really know how we have been passing our audits for the last few years.

    I'm pretty sure that all inspection equipment needs to be traceable to NIST. Is this correct?

    If so, how can i make a compelling argument for sending our thread gages and master gage bocks out for calibration? Can a CMM be used to qualify master gage blocks?

    Any help or advice would be appreciated.
     
    Roland Deschain, Mar 11, 2024
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  2. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Hello Roland and you are very welcome here. Everyone's been new, so don't fret, you're in good hands! Good question to start with!

    It's amazing how little (some) ISO 9001 CB auditors actually know about how ISO 9001 requirements are supposed to work! Passing an audit is a low bar, to be honest.

    As you will know, ISO 9001 allows for both calibration and/or verification. Calibration is a type of "super" verification which, while isn't necessary, does allow for traceability, as you correctly state. Clearly, marking anything "for reference only" is a major cop-out because it's neither verification nor calibration.

    You can only really verify gauge blocks on a cmm or Keyance and I'm not sure how thread ring gauges would be done - except expensively, compared to buying a master thread plug and using that for each size. I'm guessing the boss isn't strong on calibration techniques! If you cost the time to program the features of a thread gauge, I suspect at your own overhead rate - plus the cost of not getting paying stuff done - it's more expensive than one of the other, available options!

    Not all equipment needs to be traceable. Some basic "masters" really do, since they are used to verify other equipment against. How many sizes are we talking about for the thread gauges? Also, if you send out the whole box of jo-blocks, then you are likely wasting money, especially if you're doing them once a year or similar.
     
    Last edited: Mar 12, 2024
    Andy Nichols, Mar 11, 2024
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  3. Golfman25

    Golfman25 Well-Known Member

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    Having recently gone through years and years of outside calibration certificates, I can feel your pain. A lot of wasted time and money. So here are my thoughts.

    First, you need to figure out calibration schedules. We use our CMM every day, so we do an annual calibration by an outside provider. He comes in, does some maintenance, calibration, etc. Takes a few hours. That is our "gold standard" if you will.

    Hand gages, Mics, Calipers and such (stuff we use every day), get calibrated in house, 2x per year. But we only do those that are material to our operation -- i.e.; ones used for part approval.

    Gage blocks, pins, rings and such have always been an issue. We don't use them enough to warrant annual calibrations. We used to send alternate sets out every year. It was just a lot of work for little return. So what we ended up doing is all of our blocks, pins, etc. are verify before use. We then have a master set that is only used for our internal calibrations. We have that set on a long term calibration schedule because we only use it 2 times per year and only for calibration purposes.

    The stuff in the middle, that we may use a few times per year -- we put on a longer calibration schedule. So it may be 2-5 years before it is calibrated, depending. Good luck.
     
    Golfman25, Mar 14, 2024
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